linux-kernel - Re: [PATCH 1/3] drivers-gpu-drm-allow-to-load-edid-firmware.patch

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Date:	Thu, 26 Apr 2012 00:46:39 +0200
From:	Carsten Emde <C.Emde@...dl.org>
To:	Michael Witten <mfwitten@...il.com>
CC:	Alan Cox <alan@...rguk.ukuu.org.uk>,
	David Airlie <airlied@...ux.ie>,
	Thomas Gleixner <tglx@...utronix.de>,
	DRI <dri-devel@...ts.freedesktop.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] drivers-gpu-drm-allow-to-load-edid-firmware.patch

Michael,

> On Sun, 11 Mar 2012 22:23:22 +0100, Carsten Emde wrote:
>> On 03/11/2012 02:44 PM, Alan Cox wrote:
>>>> This patch allows to load an EDID data set via the firmware interface.
>>>> It contains data sets of frequently used screen resolutions (1024x768,
>>>> 1280x1024, 1680x1050 and 1920x1080). The requested EDID data are
>>>> specified as a module parameter of the drm_kms_helper module, e.g.
>>>> options drm_kms_helper edid_firmware=edid/1280x1024.bin or as kernel
>>>> command line parameter.
>>> What if the DRM layer and driver are compiled in. They'll come up as
>>> console before the file system so the firmware request will hang ?
>> Admittedly I did not try to compile the DRM layer and driver into the
>> kernel. However, I created an error condition by specifying a
>> non-existing EDID file. In this case, the function returns with error,
>> the mode count remains 0, and the system continues to run as if the
>> edid_firmware= parameter had not been specified.
> Unfortunately, as of at least last month, my system hangs when I try to
> use your feature (just as described by Alan Cox); the log shows that
> during the boot process, there is a one-minute hang:
>
>    [    0.175207] [drm] radeon: power management initialized
>    [   60.896507] [drm:edid_load] *ERROR* Requesting EDID firmware "edid/1920x1200.bin" failed (err=-2)
>
> Is there any way to make your feature smarter about its timing with
> relation to file system accessibility?
Sure.

Please copy your EDID data file to the directory "firmware/edid" of the 
kernel source tree, configure

CONFIG_EXTRA_FIRMWARE="edid/1920x1200.bin"
CONFIG_EXTRA_FIRMWARE_DIR="firmware"

and rebuild/reboot your kernel.

Does it work then?

	-Carsten.
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